External sulphate attack on recycled concrete: Assessment of the influence of recycled aggregate

Abstract

The performance of recycled aggregate concrete (RAC) under external sulfate attack (ESA) has not been fully clarified yet. The attached mortar on recycled aggregate particles increases the content of hydration products from Portland cement that are able to react with external sulfates. In addition, it increases the porosity of the resulting material, facilitating the penetration of ions.In this paper, we present experimental results focusing on the evaluation of the potential reactivity of recycled aggregates themselves. Weight and length variations of mortar bars made with fine recycled aggregates obtained from crushing concretes containing high and low C3A Portland cements were determined after exposure to sulfate solution at 38ºC. In addition, concrete cores with 25 mm and 75 mm in diameter exposed to sulfate solution at 20ºC were also evaluated. The results show no indication of significant reactivity of recycled aggregates with external sulfate.